INTRODUCTION 19 



is in its infancy, and many other types no doubt 

 await discovery. A recent estimate of the bulk of 

 this flora compares the inconspicuous marine or- 

 ganisms of the Sargasso Sea with the bulk of the 

 floating banks of gulf- weed that give this great tract 

 of ocean its name, with the result that the micro- 

 scopic forms enormously exceed the gulf-weed in 

 aggregate mass. The result is all the more striking 

 since it is known that the Sargasso Sea is poor in 

 these minute forms compared with many other 

 regions of the ocean. As regards the Sargasso, float- 

 ing free in this region and elsewhere, the view 

 generally adopted accounts for their presence by 

 the supposition that they have been torn from their 

 natural moorings and drifted by currents, and that 

 they slowly perish in the Sargasso Sea, to be renewed 

 by fresh supplies from the same source. The theory 

 has much to recommend it on purely oceanographical 

 grounds, but the difficulty remains that Sargassum 

 lacciferum, which composes the mass of free-float- 

 ing Sargasso, in the tropical Atlantic, has never 

 been recorded as growing attached, in a quantity 

 sufficient to account for the supply. Moreover, other 

 Sargassa do grow attached in enormous quantities, 

 but they are of only casual occurrence in a free state. 

 There is still the refuge that S. bacciferum is a mere 

 "growth-form" modified by passage down currents. 

 This, however, has no farther observation to support 

 it, and, moreover, an examination of Sargassa from 

 the centre of this still region of the ocean shows no 

 symptom of recovery of broader fronds after removal 

 from the influence of the currents that bound it. 



c 2 



